Vacuum deposition sources having heated effusion orifices

ABSTRACT

The present invention provides deposition sources that can efficiently and controllably provide vaporized material for deposition of thin film materials. Deposition sources described herein can be used to deposit any desired material and are particularly useful for depositing high melting point materials at high evaporation rates. An exemplary application for deposition sources of the present invention is deposition of copper, indium, and gallium in the manufacture of copper indium gallium diselenide based photovoltaic devices.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser.No. 61/188,671 filed Aug. 11, 2008 entitled HIGH TEMPERATURE DEPOSITIONSOURCES AND METHODS, which is hereby incorporated by reference in itsentirety for all purposes.

TECHNICAL FIELD

The present invention is directed to vacuum deposition sources. Inparticular, the present invention is directed to vacuum depositionsources having heated effusion orifices that help to prevent depositionmaterial from accumulating near such effusion orifices and restrictingflow of deposition material. A preferred exemplary deposition source inaccordance with the present invention comprises a rear-loading crucibleand a conical heat shield assembly comprising a conical cover positionedrelative to effusion orifice end of the crucible. Vacuum depositionsources in accordance with the present invention can be used in vacuumenvironments in the millitorr range as well as vacuum environmentssuitable for ultra-high vacuum applications such molecular beam epitaxy.

BACKGROUND

Compounds of copper indium diselenide (CIS) with gallium substituted forall or part of the indium (copper indium gallium diselenide or CIGS) areused in photovoltaic devices. For example, CIGS provides absorber layersin thin-film solar cells. CIGS semiconductor materials have a directband gap that permits strong absorption of solar radiation in thevisible range. CIGS cells have demonstrated high efficiencies and goodstability as compared to other absorber layer compounds such as cadmiumtelluride (CdTe) or amorphous silicon (a-Si).

Solar cell devices typically include a substrate, a barrier layer, aback contact layer, a semiconductor layer, alkali materials, an n-typejunction buffer layer, an intrinsic transparent oxide layer, and aconducting transparent oxide layer. In a device that utilizes CIGS, thesemiconductor layer includes copper, indium, gallium, and selenium. TheCIGS layers used for photovoltaic conversion need to have a p-typesemiconductor character and good charge transport properties. Thesecharge transport properties are favored by good crystallinity. The CIGSthus need to be at least partially crystallized in order to havesufficient photovoltaic properties for use in the fabrication of solarcells. Crystallized CIGS compounds have a crystallographic structurecorresponding to the chalcopyrite or sphalerite systems, generallydepending on the deposition temperature.

CIGS thin films can be deposited by various techniques, typically vacuumbased. One technique involves the use of precursors. In this technique,intermediate compounds are used and have physicochemical properties thatare distinct from those of CIGS and make them incapable of photovoltaicconversion. The precursors are initially deposited in a thin film form,and the thin film is subsequently processed to form the intended CIGSlayer. When precursor materials are deposited at a low temperature, theresulting CIGS thin films are weakly crystallized or amorphous. Thesethin films need to be annealed by supplying heat to improve thecrystallization of the CIGS and provide satisfactory charge transportproperties. At the temperatures that allow at least partialcrystallization of the CIGS, however, one of the constituent elements ofthe CIGS (selenium) is more volatile than the other elements. It istherefore difficult to obtain crystallized CIGS with the intendedcomposition and stoichiometry without adding selenium during annealingof the precursor layer. Time consuming annealing of the precursordeposits in the presence of selenium excess in the vapor phase is thusneeded to form suitable material.

Another technique for depositing CIGS thin films involves vacuumevaporation. Devices formed by this technique often have highphotovoltaic conversion efficiencies compared to techniques that useprecursor materials. Typically, co-evaporation of the copper, indium,gallium, and selenium is performed in the presence of a substrate. Thisco-evaporation technique has an advantage in that the content of galliumin the thin film light-absorbing layer can be regulated to achieve theoptimum bandgap. Evaporation is a technique that can be difficult to useon the industrial scale, however, particularly because of non-uniformityproblems with the thin film deposits over large surface areas and a lowefficiency of using the primary materials.

There are additional challenges that arise when using vacuum depositiontechniques for depositing CIGS thin films. For example, selenium reactsaggressively with many materials that are typically used in themanufacture of vacuum deposition sources especially at elevatedtemperatures. Accordingly, the materials and the mechanical design ofdeposition sources used in a selenium environment are carefullyconsidered.

Additionally, undesirable accumulation of deposition material in thevicinity of the effusion orifice of a vacuum deposition sources canoccur under certain deposition conditions. Typically, such depositionconditions include one or more of high deposition temperatures and highdeposition rates such as those used for deposition of high temperaturemetals or semiconductors materials, such as copper, for example.Continued accumulation of deposition material can reduce the area of theeffusion orifice and thereby reduce the deposition rate. Ultimately,continued accumulation of deposition material can effectively close theeffusion orifice so the deposition rate is unacceptably low ornon-existent.

SUMMARY

The present invention provides deposition sources that can efficientlyand controllably provide vaporized material for deposition of thin filmmaterials without the above-described problem related to accumulation ofdeposition material at the effusion orifice. Moreover, depositionsources in accordance with the present invention are particularly usefulfor use in a corrosive high temperature environment such as in thepresence of selenium vapor. Deposition sources described herein can beused to deposit any desired materials, however, and are particularlyuseful for depositing materials at high evaporation rates (in excess of30 grams per hour, for example) and at high temperatures (up to 1500°C., for example). An exemplary application for deposition sources of thepresent invention is deposition of copper, indium, and gallium in themanufacture of copper indium gallium diselenide based photovoltaicdevices.

Deposition sources in accordance with the present invention preferablyuse a heater made from layers of pyrolytic boron nitride and pyrolyticgraphite wherein the pyrolytic graphite functions as the resistiveelement and is sandwiched between layers of pyrolytic boron nitride.Because the resistive element is effectively encapsulated in pyrolyticboron nitride the resistive element is protected from the surroundingenvironment. Moreover, the heater is preferably designed so the heateris closely coupled with the crucible, which can help to keep the regionnear the effusion orifice of the crucible hot enough to preventundesirable condensation of deposition material near the effusionorifice. Deposition sources in accordance with the present inventionalso preferably include a conical cover that prevents any material thatfalls back to the source from creating a seed that could causedeposition material to accumulate near the effusion orifice of thedeposition source.

In an exemplary aspect of the present invention a vacuum depositionsource is provided. The vacuum deposition source preferably comprises: abase flange configured to mount the vacuum deposition source to a vacuumchamber; a crucible operatively supported relative to the base flangeand configured to hold vacuum deposition material, the cruciblecomprising a cylindrical body portion, a conical portion, and aneffusion orifice; and a heater operatively supported relative to thebase flange and at least partially surrounding the crucible, the heatercomprising a cylindrical body portion configured and positioned toprovide thermal radiation to at least a portion of the cylindrical bodyportion of the crucible and a conical portion configured and positionedto provide thermal radiation to at least a portion of the conicalportion of the crucible, the heater comprising a layered structurecomprising a pyrolytic graphite electrically resistive layer positionedbetween pyrolytic boron nitride electrically insulative layers.

In another exemplary aspect of the present invention a vacuum depositionsource is provided. The vacuum deposition source preferably comprises: abase flange configured to mount the vacuum deposition source to a vacuumchamber; a crucible operatively supported relative to the base flangeand configured to hold vacuum deposition material, the cruciblecomprising a cylindrical body portion, a conical portion, and aneffusion orifice; a heater operatively supported relative to the baseflange and at least partially surrounding the crucible, the heatercomprising a cylindrical body portion configured and positioned toprovide thermal radiation to at least a portion of the cylindrical bodyportion of the crucible and a conical portion configured and positionedto provide thermal radiation to at least a portion of the conicalportion of the crucible, the heater comprising a layered structurecomprising a pyrolytic graphite electrically resistive layer positionedbetween pyrolytic boron nitride electrically insulative layers; a liquidcooling enclosure operatively attached to the base flange at a first endof the liquid cooling enclosure and at least partially surrounding thecrucible; and a conical cover positioned at a second end of the liquidcooling enclosure opposite the first end of the cooling enclosure, theconical cover comprising an opening positioned relative to the effusionorifice of the crucible.

In yet another exemplary aspect of the present invention a vacuumdeposition source is provided. The vacuum deposition source preferablycomprises: a base flange configured to mount the vacuum depositionsource to a vacuum chamber; a crucible support assembly comprising asupport flange removably mounted to the base flange and a cruciblesupport cup supported relative to the support flange; a crucibleoperatively supported by the support cup of the crucible supportassembly and configured to hold vacuum deposition material, the cruciblecomprising a cylindrical body portion, a conical portion, and aneffusion orifice; and a heater operatively supported relative to thebase flange and at least partially surrounding the crucible, the heatercomprising a cylindrical body portion configured and positioned toprovide thermal radiation to at least a portion of the cylindrical bodyportion of the crucible and a conical portion configured and positionedto provide thermal radiation to at least a portion of the conicalportion of the crucible, the heater comprising a layered structurecomprising a pyrolytic graphite electrically resistive layer positionedbetween pyrolytic boron nitride electrically insulative layers.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this disclosure, illustrate several aspects of the presentinvention and together with description of the exemplary embodimentsserve to explain the principles of the present invention. A briefdescription of the drawings is as follows:

FIG. 1 is a perspective view of an exemplary deposition source inaccordance with the present invention and showing in particular aconical heat shield assembly comprising a conical cover.

FIG. 2 is a cross-sectional view of the deposition source shown in FIG.1 and showing in particular an exemplary liquid cooling enclosure inaccordance with the present invention.

FIG. 3 is a partial exploded view of the deposition source shown in FIG.1 and showing in particular an exemplary removable crucible supportassembly in accordance with the present invention.

FIG. 4 is a perspective view of the removable crucible support assemblyshown in FIG. 3 in accordance with the present invention.

FIG. 5 is a partial exploded view of the deposition source shown in FIG.1 and showing in particular an exemplary heater support assembly with anexemplary heater and an exemplary tubular heat shield assembly inaccordance with the present invention.

FIG. 6 is a partial exploded view of the heater support assembly andheater shown in FIG. 5 in accordance with the present invention.

FIG. 7 is an exploded view of the tubular heat shield assembly shown inFIG. 5 in accordance with the present invention.

FIG. 8 is an exploded view of the liquid cooling enclosure shown in FIG.2 in accordance with the present invention.

FIG. 9 is a partial cross-sectional view of the deposition source shownin FIG. 1 in accordance with the present invention.

FIG. 10 is a partial cross-sectional perspective view of the depositionsource shown in FIG. 1 in accordance with the present invention.

FIG. 11 is an exploded view of the conical heat shield assembly shown inFIG. 1 and showing in particular plural layers of conical heat shieldingand the conical cover in accordance with the present invention.

FIG. 12 is a partial side view of the deposition source shown in FIG. 1and showing in particular exemplary electrical contacts in accordancewith the present invention.

FIG. 13 is a partial exploded view of the deposition source shown inFIG. 1 and further showing electrical contacts in accordance with thepresent invention.

FIG. 14 is a partial exploded view of the deposition source shown inFIG. 1 and further showing electrical contacts in accordance with thepresent invention.

FIG. 15 is a partial cross-sectional perspective view of the depositionsource shown in FIG. 1 and further showing electrical contacts inaccordance with the present invention.

FIG. 16 is a partial cross-sectional perspective view of the depositionsource shown in FIG. 1 and further showing electrical contacts inaccordance with the present invention.

FIG. 17 is a partial top down cross-sectional view of the depositionsource shown in FIG. 1 and further showing electrical contacts inaccordance with the present invention.

FIG. 18 is a partial perspective view of another exemplary depositionsource in accordance with the present invention and showing inparticular electrical contacts in accordance with another exemplaryembodiment of the present invention.

FIG. 19 is a partial cross-sectional perspective view of the depositionsource shown in FIG. 18.

FIG. 20 is a schematic top down cross-sectional view of anotherexemplary deposition source in accordance with the present invention andshowing in particular electrical contacts in accordance with anotherexemplary embodiment of the present invention.

DETAILED DESCRIPTION

The exemplary embodiments of the present invention described herein arenot intended to be exhaustive or to limit the present invention to theprecise forms disclosed in the following detailed description. Ratherthe exemplary embodiments described herein are chosen and described sothose skilled in the art can appreciate and understand the principlesand practices of the present invention. Structural aspects of thepresent invention that are illustrated and described are exemplary andalternative structures that provide the desired functionality will beapparent to those of skill in the art and can be used in accordance withthe present invention.

An exemplary vacuum deposition source 10 in accordance with the presentinvention is illustrated in FIGS. 1 through 17. In an exemplaryapplication vacuum deposition source 10 is used to provide efficientdeposition of copper, indium, and gallium for forming CIGS basedphotovoltaic devices such as those used in solar cells. In suchapplication, one or more deposition sources 10 of the present inventionare used with one or more selenium deposition sources in a vacuumdeposition system (not shown) for deposition of such CIGS basedmaterials. Preferably, when deposition sources in accordance with thepresent invention are used in a selenium environment materials used forconstruction of such deposition sources are selected accordingly. Inparticular, materials that are known to corrode when in the presence ofselenium and high temperatures are preferably avoided when possible.

Deposition sources in accordance with the present invention areparticularly useful in harsh vacuum environments such as those wherecorrosive materials such as selenium are used. It is contemplated,however, that deposition sources in accordance with the presentinvention can be used for deposition of any desired material in anydesired vacuum environment including but not limited to metals,ceramics, semiconductors, and elemental materials, for example. Vacuumdeposition sources in accordance with the present invention are alsoparticularly useful in vacuum environments having a background pressureless than about 1 millitorr. Vacuum deposition sources in accordancewith the present invention can also be used in vacuum environmentshaving a background pressure in the high vacuum and ultrahigh vacuumregime such as those used in conventional thermal evaporation andmolecular beam epitaxy, for example. When deposition sources inaccordance with the present invention are used in an environment freefrom corrosive materials such as selenium, materials used forconstruction of such deposition sources are preferably selected in viewof a particular operating environment in which a deposition source is tobe used. When appropriate, conventional materials for construction ofvacuum equipment are preferably used such as stainless steel, refractorymetals, and pyrolytic boron nitride, for example.

Deposition sources in accordance with the present invention can be usedfor deposition on any desired substrates such as glass, semiconductormaterials, and/or plastic materials, for example.

Referring initially to FIG. 1 exemplary vacuum deposition source 10 inaccordance with the present invention is illustrated. Vacuum depositionsource 10 includes base flange 12, deposition source body 14, andeffusion orifice 16. Base flange 12 supports deposition body 14 andfunctions to attach deposition source 10 to a vacuum deposition system(not shown). Base flange 12 also preferably includes optional handles 13as shown in the exemplary illustrated embodiment. As is common withvacuum deposition equipment, base flange 12 preferably comprisesstainless steel.

As illustrated, deposition source 10 includes optional nipple 18 havingflange 20 attached to base flange 12. Nipple 18 also include optionalhandle 19 as shown in the exemplary illustrated embodiment. Nipple 18 istypically used to adapt deposition source 10 to a particular vacuumdeposition system (not shown). When nipple 18 is used, vacuum depositionsource 10 is attached to a vacuum deposition system (not shown) withflange 22 of nipple 18. Stainless steel construction is preferably usedfor nipple 18.

Referring to FIG. 2 generally, exemplary deposition source 10 preferablyincludes crucible 24, crucible support assembly 26, heater 28, heatersupport assembly 30, tubular heat shield assembly 32, liquid coolingenclosure 34, conical heat shield assembly 36, and conical cover 38.

Crucible 24 is removably and adjustably positioned relative to baseflange 12 with crucible support assembly 26, which can be seen in moredetail in FIGS. 3 and 4. Advantageously, crucible support assembly 26allows crucible 24 to be removed from deposition source 10 through baseflange 12 of deposition source 10. This rear loading capability allowsfor easier reloading of deposition material into crucible 24 becausedeposition source 10 does not need to be completely removed from thevacuum deposition system (not shown) as is needed for top loadingdeposition sources. Moreover, the rear loading design of depositionsource 10 of the present invention allows greater flexibility indesigning the effusion end of a deposition source because the crucibledoes not need to be removed from the effusion end of the depositionsource and can be removed from the opposite end.

Crucible 24 preferably comprises a monolithic restricted-orifice vesselcapable of holding a desired deposition material. As can be seen inFIGS. 2 and 3 crucible 24 comprises spherical end 25, cylindrical bodyportion 27, first conical portion 29, and second conical portion 31. Anexemplary preferred crucible material is pyrolytic boron nitride,however, other materials can be used for crucible 24 as would beapparent to those of skill in the art. Pyrolytic boron nitride is apreferred material for vacuum deposition crucibles as well as forcomponents used for vacuum deposition equipment. Pyrolytic boron nitrideis generally inert, can withstand high temperatures, is generally cleanand does not contribute undesirable impurities to the vacuumenvironment, is generally transparent to certain wavelengths of infraredradiation, and can be fabricated into complex shapes, for example.

Crucible material is preferably selected based on parameters such asmaterial compatibility, operating temperature, thermal conductivity, andelectrical conductivity, for example. Alternatives crucible materialsthat can be used include graphite, ceramics, and refractory metals, forexample. Crucible 24 does not need to be monolithic and does not need toutilize the restricted-orifice design of exemplary crucibles 24.Crucible material and geometry is preferably selected based on factorssuch as the deposition material to be used in the environment in whichthe crucible will be located. Exemplary crucibles are described in U.S.Pat. No. 5,820,681, U.S. Pat. No. 5,827,371, and U.S. Pat. No.5,932,294, the entire disclosures of which are incorporated by referenceherein for all purposes. Crucibles that can be used with depositionsources in accordance with the present invention are available fromVeeco Instruments, Inc. of St. Paul, Minn. and Momentive PerformanceMaterials of Strongville, Ohio.

Referring to the perspective view of FIGS. 3 and 4 and thecross-sectional view of FIG. 2 crucible support assembly 26 includessupport flange 40 that removably and sealingly mates to base flange 12of deposition source 10. Support flange 40 preferably comprisesstainless steel as is conventionally used for vacuum equipment.Preferably, as can be seen in FIG. 2 an o-ring seal 42 is used betweensupport flange 40 and base flange 12. O-ring seals are preferred overmetal gaskets when used in certain corrosive environments such as in thepresence of selenium vapor, for example. Alternatively, depending on theapplication, a Conflat® style seal can be used, for example, which sealcomprises flanges having knife-edges that embed into a soft metal sealgasket such as a copper or nickel gasket or the like. Appropriatesealing techniques for various vacuum applications are well known tothose skilled in the art of vacuum equipment.

Further referring to FIGS. 2, 3, and 4, crucible support assembly 26includes vacuum feed-through 44 that provides linear motion throughsupport flange 40 from the ambient atmosphere side of support flange 40to the vacuum side of support flange 40. Vacuum feed-through 44preferably includes shaft 46 coupled to shaft assembly 48 and cruciblesupport cup 50 attached to shaft assembly 48.

Shaft assembly 48 and crucible support cup 50 are preferably made fromgraphite while shaft 46 preferably comprises a dissimilar material suchas titanium or stainless steel to provide a thermal break to helpprevent heat from damaging feed-through 44, which preferably comprisesan o-ring seal as noted below. Graphite is a preferred material becausegraphite provides a readily machinable material resistant to reactionwith corrosive materials such as selenium and the like as well asdeposition materials such as copper, indium, and gallium and is tolerantto the necessary process temperatures. Such processing temperatures, forexample, can be as high as 1500° C. for some applications. Graphite alsohas thermal expansion properties compatible with pyrolytic boronnitride. Graphite is also relatively soft and thus provides a suitablesupport for crucibles made from pyrolytic boron nitride or other fragileor otherwise delicate materials. Graphite material is available fromPoco Graphite, Inc. of Decatur, Tex., for example. A preferred graphitematerial is referred to as fine grain isostatically molded graphite.

Vacuum feed-through 44 also preferably includes adjustment knob 52 andlock nut 54. Rotation of adjustment knob 52 causes shaft 46, shaftassembly 48, and crucible support cup 50 to linearly translate along thedirection indicated by reference numeral 56. Vacuum feed-through 44preferably comprises a stainless steel shaft (shaft 46), threadedconnection to provide linear motion, and an o-ring based vacuum seal.Vacuum feed-through 44 is exemplary and any device or mechanism that canprovide linear motion of crucible support 50 along the directionindicated by reference to a 56 can be used. Such linear motionfeed-through devices are well known to those skilled in the art ofvacuum equipment.

Crucible support assembly 26 also includes liquid cooling enclosure 58and heat shield assembly 60. Liquid cooling enclosure 58 and heat shieldassembly 60 are preferably designed to shield vacuum feed-through 44from direct radiant heat and help prevent o-ring seal of linearfeed-through 44 from excess heat. Liquid cooling enclosure 58 and heatshield assembly 60 illustrate exemplary structure for providing suchshielding and any desired structure that functions to help provide thedesired cooling and heat shielding functionality can be used. As can beseen in FIG. 2, liquid cooling enclosure 58 preferably comprises insidewall 60 and outside wall 62 spaced apart from inside wall 60. Liquidcooling enclosure 58 is preferably welded to support flange 40 but otherconnection techniques such as those including use of removable fastenerscan be used to attach liquid cooling enclosure 58 to support flange 40.Liquid cooling enclosure 58 preferably comprises stainless steel.

Heat shield assembly 64 preferably comprises plural layers of refractorymetal sheets such as those made from tantalum, tungsten, niobium, andmolybdenum, for example. Such refractory metal sheets may be flat,knurled, dimpled, or otherwise embossed to help space apart adjacentsheets to provide thermal breaks between adjacent sheets. Preferably,plural dimpled sheets are used. In another exemplary embodiment acombination of alternating flat and dimpled sheets is used. Alternativesmaterials that can be used include ceramics and graphite, for exampleRefractory metal sheets are available from Plansee LLC of Franklin,Mass., for example.

Heat shield assembly 64 is preferably attached to tube assembly 58 andincludes opening 70 that allows shaft assembly 48 to translate alonglinear direction 56 discussed above. An exemplary attachment techniqueis illustrated in FIG. 4 and includes using wire 66 to attach heatshield assembly 64 to anchor 68 of outside wall 62 of tube assembly 58at plural locations. Use of wire 66 and anchor 68 to attach heat shieldassembly 64 to outside wall 62 of tube assembly 58 is exemplary andother attachment techniques that achieve the same result can be usedsuch as those including use of fasteners or spot welding or the like.

Vacuum deposition source 10 preferably comprises an optional alignmentsystem to aid in positioning crucible support assembly 26 relative tobase flange 12 during assembly as can be seen with reference to FIGS. 2and 3. Base flange 12 includes alignment rods 72 extending from baseflange 12. Crucible support assembly 26 includes alignment tubes 74 thatextend from support flange 40 and correspond with openings 76 providedin support flange 40. During assembly, alignment rods 72 are alignedwith and inserted into openings 76 and are subsequently linearly guidedby alignment tubes 74 as crucible support assembly 26 is moved intoposition to be attached to base flange 12.

As can be seen in FIG. 2, crucible support assembly 26 also preferablyincludes thermocouple 78 that functions to measure temperature andprovide control feedback. Thermocouple 78 is removably attached to port80 of support flange 40. Thermocouple 78 includes junction 82 that ispreferably positioned within heater 28 adjacent to crucible support cup50. Preferably, thermocouple 78 is encapsulated in pyrolytic boronnitride, which helps to protect thermocouple 78 from depositionmaterials and also helps to provide mechanical support for thermocouple78. An appropriate thermocouple can be selected based on the particulartemperature range to be measured as well as the vacuum environment inwhich the thermocouple will be used. For example, a Type-C thermocouplecan be used. Any desired temperature measurement device can be used,however, as such devices are well known to those skilled in the art ofvacuum equipment. Temperature measurement devices includingthermocouples are available from Omega Engineering, Inc. of Stamford,Conn., for example.

Referring to FIGS. 5 and 6 in particular, heater 28 is preferablyremovably and adjustably positioned relative to base flange 12 by heatersupport assembly 30. Heater support assembly 30 preferably comprisessupport base 84, heat shield assembly 86, and height adjustment legs 88.Support base 84 comprises a generally cylindrical ring-like structurehaving recessed region 90 that receives end 92 of heater 28. Preferably,recessed region 90 and end 92 are designed to have a close sliding fit.Threaded openings 94 of support base 84 along with openings 96 of heater28 when end 92 of heater 28 is positioned in recessed region 90 ofsupport base 84. Fasteners 98 comprise a threaded portion 100 and anon-threaded portion 102. When positioned in openings 94 of support base84 non-threaded portions 102 of fasteners 98 engage with openings 96 ofheater 28 to secure heater 28 in place relative to heater support base84. Heater support base 84 and fasteners 98 preferably comprisesgraphite. Graphite material is available from Poco Graphite, Inc. ofDecatur, Tex., for example. A preferred graphite material is referred toas fine grain isostatically molded graphite.

Heater support assembly 30 further preferably comprises plural rotatableheight adjustment legs 88 that rotatably engage with respective fixedsupport legs 104 of base flange 12. Adjustment legs 88 each comprisethreaded portion 106 that threads into each respective threaded bore 108of heater support base 84. Adjustment legs 88 also each include bore 110that rotatably engages with a shaft portion (not shown) of eachrespective fixed support leg 104 of base flange 12. Height adjustmentlegs 88 preferably comprise graphite. Graphite material is availablefrom Poco Graphite, Inc. of Decatur, Tex., for example. A preferredgraphite material is referred to as fine grain isostatically moldedgraphite. Fixed support legs 104 preferably comprise stainless steel andare preferably welded or otherwise secured to base flange 12.

In use, rotation of height adjustment legs 88 varies the height ofsupport base 84 relative to base flange 12 as well as the height oforifice 16 of crucible 24 relative to base flange 12. Such heightadjustment is described in further detail below. Height adjustment legs88 also each include opening 112 that can be aligned with acorresponding opening (not shown) of each fixed leg 104. A suitable wireor the like (not shown) is preferably positioned in opening 112 and thecorresponding opening of fixed leg 104 to prevent rotation of heightadjustment 88 relative to fixed leg 104.

Continuing to refer to FIGS. 5 and 6, heater support assembly 30 alsocomprises heat shield assembly 86 as noted above. Heat shield assembly86 preferably comprises support plate 114 and plural layers ofrefractory metal sheets 116 such as those made from tantalum, tungsten,niobium, and molybdenum, for example. With reference to FIG. 6, inparticular, heat shielding assembly 86 includes openings 118 thatreceive height adjustment legs 88. Height adjustment legs 88 eachcomprise shoulder 120, which supports heat shield assembly 86 whenassembled as shown in FIG. 5. Height adjustment legs 88 also eachcomprise channel 122 spaced apart from shoulder 120 and which canreceive a wire or retaining clip (not shown) to secure heat shieldassembly 86 relative to height adjustment legs 88. Support plate 114preferably comprises pyrolytic boron nitride. Alternative materials thatcan be used include ceramics and graphite, for example Refractory metalsheets 116 may be flat, knurled, dimpled, or otherwise embossed to helpspace apart adjacent sheets to provide thermal breaks between adjacentsheets. Preferably, plural and knurled (or dimpled or the like) sheetsare used. In another exemplary embodiment a combination of alternatingflat and dimpled sheets is used.

Vacuum deposition source 10 also preferably includes tubular heat shieldassembly 32 as noted above. Heat shield assembly 32 functions to helpprevent radiant heat from escaping from vacuum deposition source 10,which helps to improve efficiency and controllably of vacuum depositionsource 10 during operation. Heat shield assembly 32 also functions tohelp position and support heater 28 as explained in more detail below.

Referring to FIG. 7, exemplary tubular heat shield assembly 32 comprisessupport rings 124, first heat shield 126, and second heat shield 128.Support rings 124 preferably comprise plural arcuate sections 130,Support rings 124 may, however, comprise a single monolithic ringstructure as plural sections are not required but are used in apreferred embodiment to provide efficient use of material. Althoughthree support rings 124 are illustrated in exemplary tubular heat shieldassembly 32, it is contemplated that any desired number of support ringscan be used. Preferably, support rings 124 comprise pyrolytic boronnitride but other materials can be used.

Preferably, arcuate sections 130 are interconnected using refractorymetal wire that passes through openings in overlapping ends of adjacentarcuate sections 130. Any desired attachment technique can be used,however, such as by using fasteners or the like, for example. Asillustrated, support rings 124 also optionally comprise openings 132that function to provide conductance for pumping. In one preferredembodiment, at least one of support rings 124 provides a close fit witheither 28. Preferably, such support ring includes an identifying mark orthe like such as by using square openings in contrast with roundopenings 132, for example.

Support rings 124 additionally include plural tabs 134 spaced apartaround the circumference of the outside diameter of support rings 124.When assembled, tabs 134 mate with slots 136 provided in first andsecond heat shields 126 and 128, respectively. Wires 125 are preferablywrapped around first and second heat shields 126 and 128 and jointogether such as by twisting respective ends together. Preferably, wires125 are also engaged with tabs 134. Edges of first and second heatshields 126 and 128 may be overlapped or may be butted together.

First and second heat shields 126 and 128, respectively, preferablycomprise arcuate refractory metal sheets such as those made fromtantalum, tungsten, niobium, and molybdenum, for example. While two heatshields are illustrated in the exemplary heat shield assembly 32 it iscontemplated that any number of arcuate heat shield portions havingplural seams can be used to form heat shield assembly 32 including useof a single sheet of refractory material that is rolled to form acylindrical structure having a single seam. First and second heatshields 126 and 128, respectively, each comprise a single layer, asshown. It is contemplated, however, that plural layers of refractorymetal material can be used. For example, plural layers of alternatingflat and knurled (or dimpled or the like) refractory metal sheets can beused.

Referring back to FIGS. 5 and 6, support base 84 comprises outsidesurface 140 that preferably removably and slidingly couples with insidesurface 142 of heat shield assembly 32. When assembled, end 144 of heatshield assembly 32 preferably rests against shoulder 146 of support base84. Preferably, outside surface 140 of support base 84 and insidesurface 142 of heat shield assembly 32 are designed to have a slidingfit. Such a sliding fit is exemplary and it is contemplated that othercoupling techniques can be used to couple heat shield assembly 32 withsupport base 84 such as by using one or more of fasteners, pins, andmechanical devices, for example.

With reference to the cross-sectional view of FIG. 2 and the explodedview of FIG. 8, liquid cooling enclosure 34 preferably comprises insideand outside spaced apart walls, 146 and 148, respectively, end ring 149,and mounting flange 150. Preferably, walls 146 and 148, end ring 149,and mounting flange 150 comprise stainless steel. Inside and outsidespaced apart walls, 146 and 148, respectively, at least partially definefluid channel 152. Fluid channel 152 is in fluid communication withtubes 154 that allow a desired cooling fluid, such as water, forexample, to be circulated through fluid channel 152. Liquid coolingenclosure 34 functions to help prevent radiant heat from escaping fromvacuum deposition source 10, which helps to improve efficiency andcontrollably of vacuum deposition source 10 during operation.

When assembled, mounting flange 150 is attached to base flange 12 ofdeposition source 10 using conventional threaded fasteners or the like.Tubes 154 pass through base flange 12 via sealing feed-throughs (notvisible). Such feed-throughs are conventional and well-known andtypically include an o-ring and ferrule that provide an appropriatevacuum seal suitable for the desired vacuum level and operatingtemperatures. Suitable feed-throughs are available from Swagelok, FluidSystem Technologies of Solon, Ohio, for example.

Referring to the exploded view of FIG. 8 and the detail views of FIGS. 9and 10, in particular, liquid cooling enclosure 34 preferably comprisesheat shield sheets 156, heat shield sheets 158, and support ring 162.When assembled, heat shield sheets 156 and 158 preferably form acylindrical layered assembly 160. Heat shield sheets 156 and 158 arepreferably attached to support ring 162 and can be attached to eachother, if desired, such as by using one or more of refractory metalwire, fasteners, clips, and spot welding.

As illustrated, heat shield sheets 156 and 158 are provided in pairs andare preferably arranged so an overlapping layer covers seams betweenends of sheets. Heat shield sheets 156 and 158 do not need to beprovided as pairs, however, and can be provided as any number of arcuatesheet portions comprising plural seams or as a single sheet comprising asingle seam. Although heat shield sheets 156 and 158 are illustrated asproviding three layers of heat shielding, any number of layers can beused to achieve a desired heat shielding function. For example, plurallayers of alternating flat and knurled (or dimpled or the like)refractory metal sheets can be used.

Cylindrical layered assembly 160 is preferably positioned inside liquidcooling enclosure 34 as can be seen in the cross-sectional detail viewsof FIGS. 9 and 10. As shown, heat shield sheets 156 and 158 are incontact with support ring 162. Support ring 162 engages with end ring149 of liquid cooling enclosure 34, as shown, preferably to securecylindrical layer assembly 160 relative to liquid cooling enclosure 34.Preferably, as can be seen in FIG. 8, cylindrical layered assembly 160is also held in place within liquid cooling enclosure 34 using pluralholding clips 164 that are preferably spot welded to the inside wall 146of liquid cooling enclosure 34. Engagement between support ring 162 andend ring 149 and use of holding clips 164 as illustrated is exemplaryand any suitable structure can be used to provide appropriate heatshielding for vacuum deposition source 10.

As shown, cylindrical layered assembly 160 extends along a portion ofthe length of liquid cooling enclosure 34 less than the overall lengthof liquid cooling enclosure 34. Cylindrical layered assembly 160 can,however, be designed to extend along any desired portion of inside wall146 of liquid cooling enclosure 34. Also, it is contemplated thatcylindrical layer assembly 160 can comprise plural sections that areassembled or positioned relative to each other to form a structurehaving a desired length.

Heat shield sheets 156 and 158 as well as support ring 162 preferablycomprise refractory metal sheets such as those made from tantalum,tungsten, niobium, and molybdenum, for example. In one exemplarypreferred embodiment heat shield sheets 156 comprise molybdenum and heatshield sheets 158 comprise tungsten and support ring 162 comprisestantalum. In such exemplary preferred embodiment, heat shield sheets 158form the innermost layer of cylindrical layered assembly 160. That is,heat shield sheets 156 preferably surround heat shield sheets 158. Sucharrangement is exemplary and heat shield sheets 156 and 158 can bearranged in any desired order, comprise any desired material, andcomprise any desired knurling, dimpling, or embossing to achieve adesired heat shielding function.

As noted above, vacuum deposition source 10 includes conical heat shieldassembly 36 and conical cover 38. Conical heat shield assembly 36 andconical cover 38 can be seen in cross-section in FIGS. 9 and 10 and canbe seen as an exploded perspective view in FIG. 11. Conical heat shieldassembly 36 preferably comprises plural conical heat shield sheets 166and conical base 168. Preferably, conical heat shield sheets 166 andconical base 168 are made from refractory metals such as tantalum,tungsten, niobium, and molybdenum, for example. In an exemplarypreferred embodiment, conical heat shield sheets 166 comprise molybdenumand conical base 168 comprises tantalum. Also, in an exemplary preferredembodiment, conical heat shield sheets 166 comprise one or more ofknurling, dimpling, and embossing. Although conical heat shield sheets166 are illustrated as providing three layers of heat shielding, anynumber of layers can be used to achieve a desired heat shieldingfunction. Also, plural layers of alternating flat and knurled (ordimpled or the like) refractory metal sheets can be used. Theillustrated embodiment of FIG. 11 is exemplary and heat shield sheets166 can be arranged in any desired order, comprise any desired material,and comprise any desired knurling, dimpling, or embossing to achieve adesired heat shielding function.

Conical base 168, as can be seen in FIGS. 9, 10, and 11, comprisesannular lip 170, opening 172, and end 174. When assembled as shown inFIGS. 9 and 10, end 174 rests on support ring 162 and opening 172 ispositioned over heater 28. Conical heat shield sheets 166 preferablyrest on and are supported by conical base 168, as illustrated in theexemplary embodiment. Annular lip 170 helps to retain and positionconical heat shield sheets 166 relative to conical base 160. Preferably,conical base 168 and conical heat shield sheets 166 are held in place bygravity and by conical cover 38 as noted below. If desired, however,fasteners, holding devices, retaining devices, and the like may be usedto secure any of conical base 168 and conical heat shield sheets 166relative to one or more of each other and end ring 149.

Continuing to refer to FIGS. 9, 10, and 11, conical cover 38 preferablycomprises opening 172, conical portion 174, and cylindrical portion 176.When assembled as shown in FIGS. 9 and 10, cylindrical portion 174 mateswith recessed portion 178 of end ring 149 of liquid cooling enclosure34. Opening 172 is positioned over heater 28 and preferably rests onannular lip 170 of conical base 168. Assembled as such, conical cover 38helps to trap conical heat shield sheets 166 between support ring 162and conical cover 38. Preferably, cylindrical portion 176 and recessedportion 178 of end ring 149 are designed to provide a close friction fitwhen assembled together. That is, preferably friction betweencylindrical portion 176 and recessed portion 178 functions to holdconical cover 38 removably in place on end ring 149 without the use ofadditional fasteners or holding devices. It is contemplated, however,that any desired fasteners, holding devices, retaining devices, and thelike may be used to secure conical cover 38 to end ring 149.

In an exemplary embodiment, conical cover 38 comprises pyrolytic boronnitride. It is contemplated, however, that conical cover 38 may compriseany desired material depending on the particular application ofdeposition source 10. Exemplary materials that can be used to formconical cover 38 include refractory metals and ceramics, for example.Pyrolytic boron nitride is a preferred material for construction ofcomponents used for vacuum deposition. Pyrolytic boron nitride isgenerally inert, can withstand high temperatures, is generally clean anddoes not contribute undesirable impurities to the vacuum environment, isgenerally transparent to certain wavelengths of infrared radiation, andcan be fabricated into complex shapes, for example.

As noted above in the Background section, undesirable accumulation ofdeposition material in the vicinity of the effusion orifice of vacuumdeposition sources can occur under certain deposition conditions.Typically, such deposition conditions include one or more of highdeposition temperatures and high deposition rates such as those used fordeposition of metals or semiconductors materials, such as copper,indium, and gallium, for example. For purposes of the present invention,high deposition temperatures refer to the operating temperature of theregion near the effusion orifice of a crucible. Continued accumulationof deposition material can reduce the area of the effusion orifice andthereby reduce the deposition rate. Ultimately, continued accumulationof deposition material can effectively close the effusion orifice so thedeposition rate is unacceptably low or non-existent.

Deposition sources in accordance with the present invention such asexemplary deposition source 10 can advantageously provide highdeposition rates at high operating temperatures of materials without theabove-described problem related to accumulation of deposition materialat the effusion orifice. For example, as can be seen in FIGS. 9 and 10,heater 28 includes cylindrical portion 180 and conical portion 182.Conical portion 182 of heater 28 is preferably designed to provideuniform radiant heat to first and second conical portions, 29 and 31,respectively of crucible 24. Such uniform heating can be accomplished bydesigning heater 28 to be closely fit or otherwise slidingly engagedwith crucible 24, provide heating to substantially all surfaces ofcrucible 24, and by designing heat shielding that helps to keep radiantheat within a predetermined region of the deposition source 10. Whendesigned as such, cold surfaces of crucible 24 are minimized andundesirable condensation of deposition material on the inside surface ofcrucible 24 is accordingly minimized or eliminated.

Another aspect of the present invention that is believed to help tominimize or eliminate the above-described problem related toaccumulation of deposition material at the effusion orifice relates toconical cover 38. Because of the conical shape of conical cover 38, anyparticles that might be ejected from effusion opening 16 and land onconical cover 38 will tend to slide off of conical cover 38. Preferably,the slope of conical cover 38 is selected based on factors such as aparticular deposition material to be used and the angle at whichdeposition source 10 is positioned in a vacuum deposition system. In apreferred exemplary embodiment, the angle of deposition source 10 isless than the angle of conical cover 38. In a preferred exemplaryembodiment the angle of deposition source 10 as measured with respect tovertical is less than 40° and more preferably less than 30°.Determination of the geometry of conical cover 38 and the angle ofdeposition source 10 can be determined empirically for the particulardeposition material and vacuum environment.

Yet another aspect of the present invention that is believed to help tominimize or eliminate the above-described problem related toaccumulation of deposition material at the effusion orifice relates tothe relative positions of conical cover 38 and heater 28. Referring toFIG. 9, edge 184 of heater 28 preferably extends past edge 186 ofconical cover 38. In an exemplary embodiment, edge 184 of heater 28preferably extends past edge 186 of conical cover 38 by approximately0.0-5.0 millimeters. In another exemplary embodiment, edge 184 of heater28 preferably extends past edge 186 of conical cover 38 by approximately2.0-5.0 millimeters. In yet another exemplary embodiment, edge 184 ofheater 28 preferably extends past edge 186 of conical cover 38 byapproximately 2.0-2.4 millimeters. The ranges indicated above areexemplary and the distance by which edge 184 of heater 28 extends pastedge 186 of conical cover 38 can also be determined empirically for theparticular deposition material and vacuum environment.

Adjustment of edge 184 of heater 28 with respect to edge 186 of conicalcover 38 can be performed using height adjustment legs 88 of heatersupport assembly 36. Referring back to FIG. 5, height adjustment legs 88can be rotated with respect to fixed legs 104 to translate heatersupport base 84 and heater 28 relative to the base flange 12.Preferably, a fixture (not shown) is used to set the height of edge 184of heater 28 with respect to a known surface such as a surface of baseflange 12.

Yet another aspect of the present invention that is believed to help tominimize or eliminate the above-described problem related toaccumulation of deposition material at the effusion orifice relates tothe relative positions of heater 28 and crucible 24. Referring to FIG.9, edge 188 of crucible 24 preferably extends past edge 184 of heater28. In an exemplary embodiment edge 188 of crucible 24 preferablyextends past edge 184 of heater 28 by approximately 0.0-2.0 millimeters.In another exemplary embodiment edge 188 of crucible 24 preferablyextends past edge 184 of heater 28 by approximately 0.0-2.0 millimeters.In another exemplary embodiment edge 188 of crucible 24 preferablyextends past edge 184 of heater 28 by approximately 0.2-1.0 millimeters.In yet another exemplary embodiment edge 188 of crucible 24 preferablyextends past edge 184 of heater 28 by approximately 0.2-0.5 millimeters.The ranges indicated above are exemplary and the distance by which edge188 of crucible 24 extends past edge 184 of heater 28 can also bedetermined empirically for the particular deposition material and vacuumenvironment.

Adjustment of edge 188 of crucible 24 with respect to edge 184 of heater28 can be performed using adjustment knob 52 of crucible supportassembly 26. Referring to FIG. 2 rotation of knob 52 translates cruciblesupport cup 50 and crucible 24 relative to base flange 12. When adesired position for crucible 24 is obtained lock not 54 is engaged tolock the position of crucible 24.

Heater 28 preferably comprises a monolithic heating device comprisingpyrolytic graphite conductive material sandwiched between insulatingpyrolytic boron nitride. Such heaters are available from MomentivePerformance Materials of Strongsville, Ohio. Preferably, heater 28includes two distinct serpentine resistive elements that provide twodistinct heating zones that can be controlled independently from eachother. One heating zone is preferably used to heat cylindrical portion180 and the second heating zone is preferably used to heat conicalportion 182. Advantageously, conical portion 182 can be operated at ahigher temperature than cylindrical portion 180, which can help preventcondensation of deposition material near the effusion orifice 16 ofcrucible 24. It is contemplated that heater 28 may comprise any desirednumber of resistive elements including a single resistive element.

Referring now to FIGS. 12-17 generally, and FIGS. 12-13 in particular,support base 84 further preferably comprises cutout regions 190 thatalign with electrical contacts 192 of heater 28 when end 92 of heater 28is positioned in recessed region 90 of support base 84. As illustrated,heater 28 comprises four electrical contacts 192 that provide power totwo distinct resistive elements. Power is provided to electricalcontacts 192 via power feed-throughs 194 that are preferably removablycoupled with base flange 12. Power feed-throughs 194 each comprise powerconductor 196, which typically comprises a molybdenum post and an o-ringvacuum seal.

Electrical contacts 192, as can be seen in FIG. 6, each comprise anexposed region of the associated graphite resistive element. Because end92 of heater 28 is generally cylindrical, electrical contacts 192comprise a cylindrical curvature having a known radius. Accordingly,structure used for electrical connection to cylindrically curvingelectrical contacts 192 is preferably designed to maximize contact areawith electrical contacts 192 and provide consistent pressure toelectrical contacts 192 throughout the operating temperature range ofdeposition source 10.

Power feed-throughs 194 are electrically removably connected to powerstraps 198 by flexible power cables 200. Preferably, power straps 198are cylindrically curved to correspond with the radius of end 92 ofheater 28 and taking into consideration the thickness of conductivewasher 226 (described below). Cable connectors 202 receive flexiblepower cables 200 and power conductors 196 and function to clamp flexiblepower cables 200 to power conductors 196. Insulating power strapisolators 204 are preferably positioned on power conductors 196 belowcable connectors 202, as illustrated. Insulating power strap isolators204 each include curved slot 206 that receives end 208 of each powerstrap 198 and helps to hold each power strap 198 in place. In apreferred embodiment, insulating power strap isolators 204 comprisepyrolytic boron nitride although it is contemplated that otherinsulating materials can be used. Alternative structures for positioningends 208 of power straps 198 can also be used. Use of cable connectors202 and flexible power cables 200 illustrates an exemplary technique toremovably electrically connect power conductors 196 to power straps 198and those of skill in the art will recognize that other suitabletechniques can be used to make such connection such as the use of one ormore of alternative clamping structures, fasteners, connectors, and spotwelding, for example.

Flexible power cables 200 are connected to power straps 198 with cableclamps 210. As illustrated, cable clamps 210 comprise clamping plates212 and fasteners 214 that function to compressively clamp flexiblepower cables 200 to power straps 198. Cable clamps 210 illustrates anexemplary technique to removably electrically connect flexible powercables 200 to power straps 198 and those of skill in the art willrecognize that other suitable techniques can be used to make suchconnection such as the use of one or more of alternative clampingstructures, fasteners, connectors, and spot welding, for example.Preferably, a vacuum deposition source 10 is used in the presence of acorrosive vapor such as selenium, cable clamps 210 preferably comprisemolybdenum with a stainless steel screw. Power straps 198 preferablycomprise tungsten. Power cables 200 preferably comprise multi-strandedmolybdenum wire.

In each connection, power strap 198 is preferably electrically removablyconnected to electrical contact 192 of heater 28 as illustrated by theexemplary connection technique shown in FIGS. 13-17. Power strap 198preferably passes through notch 216 provided in support base 84.Electrical connection to electrical contact 192 is preferably maintainedusing spring 218 and loading pins 220 provided at each end of spring218. Spring 218 applies spring force to pressure pin 222, which appliespressure to contact washer 224. As can be seen best in thecross-sectional view of FIG. 15, power strap 198 is preferablysandwiched between contact washer 224 and conductive washer 226.

As illustrated in the exemplary embodiment, loading pins 220 eachpreferably comprise cylindrical shoulder 236 rotatably positioned inbore 230 of support base 84. Referring to the cross-sectional view ofFIG. 16, cylindrical shoulder 228 of each spring loading pin 220includes opening 232 that receives retaining wire 234 that helps to holdspring loading pin 220 in place. It is contemplated that other retainingstructure could be used such as use of a retaining clip and groove orthe like. Referring back to FIG. 14, each spring loading pin 220 alsopreferably comprises flat portion 236 that engages with surface 238 ofspring 218 when assembled, such as is illustrated in FIGS. 15 and 16.Varying the location of flat portion 236 can be used for adjustment ofspring force.

Referring now to FIGS. 14 and 15, each pressure pin 222 preferablycomprises head portion 240 and post portion 242. Post portion 242 ofeach pressure pin 222 preferably passes through opening 244 of contactwasher 224, opening 246 of conductive washer 226, and opening 248 ofheater 28 associated with each electrical contact 192. Preferably,surface 243 of head portion 240 comprises a spherically curving surfaceand is in contact with surface 250 of spring 218. A spherically curvingsurface preferred because a spherically curving is not orientationdependent when contacting surface 250. Preferably, the radius ofspherically curving surface 243 comprises the radius that is less thanor equal to than the distance that spring 218 needs to flex.

Surface 252 of head portion 240 preferably comprises a flat surface thatmates with flat surface 253 of contact washer 244. Surface 257 ofcontact washer 224 preferably comprises a cylindrically curving surfaceand preferably has a radius determined by considering the radius ofelectrical contact 192, thickness of conductive washer 226, andthickness of power strap 198. Power strap 198 also preferably at acylindrically curving shape that corresponds with the radius ofelectrical contact 192.

Springs 218 preferably comprise a resilient material that can maintainits ability to apply consistent pressure throughout the operatingtemperature range of deposition source 10. An exemplary preferredmaterial comprises pyrolytic boron nitride because pyrolytic boronnitride is vacuum compatible, insulating, and can maintain a springforce at high temperatures. Other materials that can be used includeinsulating materials having suitable elastic properties, for example.

As shown in the exemplary illustrated embodiment, springs 218 preferablycomprise a generally rectangular plate. The dimensions, geometry, andthickness of springs 218 are preferably designed to provide the desiredspring force. Suitable characteristics for springs 218 can be determinedempirically. Preferably, in an exemplary embodiment, a load of betweenabout 3 to 8 pounds, as applied to electrical contacts 192, is used.Springs 218 may have any desired geometry, however such as thatincluding serpentine structures or the like. Also, plural layers ofmaterial can be used to form springs 218 such as to provide a leafspring structure, for example.

Loading pins 220, pressure pin 222, and contact washer 224 preferablycomprise graphite. Other suitable materials can be used, however, forloading pins 220, pressure pin 222, and contact washer 224. Conductivewasher 226 preferably comprises graphite. Other suitable materials canbe used, however, for conductive washer 226. Graphite material isavailable from GrafTech Advanced Energy Technology, Inc. of Lakewood,Ohio. One preferred graphite material is referred to as nuclear gradeGTA material.

In FIGS. 18 and 19, another exemplary electrical contact assembly thatcan be used in accordance with the present invention is illustrated. Inthe embodiment illustrated in FIGS. 18 and 19, a flat power strap 254 isused instead of the arcuate power strap 198 described above. As shown,loading pins 220 and spring 218 apply force to pressure pin 222 in asimilar manner as described above. Flat power strap 254 is preferablysandwiched between pressure pin 222 and conductive washer 256.Conductive washer 256 is in contact with contact washer 258, which is incontact with conductive washer 226. Conductive washer 226 contactselectrical contact 192 (not visible in FIGS. 18 and 19) of heater 28.

In FIG. 20, another exemplary electrical contact assembly that can beused in accordance with the present invention is illustrated. In theembodiment illustrated in FIG. 20, spring 260 is positioned insideheater 262. Pressure pin 264 applies pressure to contact washer 266 andarcuate power strap 268 is sandwiched between contact washer 266 andconductive washer 270. Conductive washer 270 is in contact with anelectrical contact (not shown) of heater 262. Pressure pin 264 includespost portion 272 that passes through contact washer 266, arcuate powerstrap 268, conductive washer 270, heater 262, and spring 260. End 274 ofpost portion 272 includes retaining clip 276 and loading tube 278 thatfunction to maintain pressure of conductive washer 270 with theelectrical contact (not shown) of heater 262 by the spring forceprovided by spring 260. Spring 260 may comprise a pyrolytic boronnitride spring as described above.

Vacuum deposition sources that can use electrical contacts described inthe present invention are described in Applicant's co-pending US PatentApplication entitled Electrical Contacts For U With Vacuum DepositionSources, filed on Aug. 11, 2009 and having Ser. No. 12/539,458, theentire disclosure of which is incorporated by reference herein for allpurposes.

The present invention has now been described with reference to severalexemplary embodiments thereof. The entire disclosure of any patent orpatent application identified herein is hereby incorporated by referencefor all purposes. The foregoing disclosure has been provided for clarityof understanding by those skilled in the art of vacuum deposition. Nounnecessary limitations should be taken from the foregoing disclosure.It will be apparent to those skilled in the art that changes can be madein the exemplary embodiments described herein without departing from thescope of the present invention. Thus, the scope of the present inventionshould not be limited to the exemplary structures and methods describedherein, but only by the structures and methods described by the languageof the claims and the equivalents of those claimed structures andmethods.

What is claimed is:
 1. A vacuum deposition source comprising: a baseflange configured to mount the vacuum deposition source to a vacuumchamber; a crucible operatively supported relative to the base flangeand configured to hold vacuum deposition material, the cruciblecomprising a cylindrical body portion, a conical portion, and aneffusion orifice; a heater operatively supported relative to the baseflange and at least partially surrounding the crucible, the heatercomprising a cylindrical body portion configured and positioned toprovide thermal radiation to at least a portion of the cylindrical bodyportion of the crucible, the heater comprising a layered structurecomprising a pyrolytic graphite electrically resistive layer positionedbetween pyrolytic boron nitride electrically insulative layers; and acooling enclosure operatively attached to the base flange at a first endof the cooling enclosure and extending along and at least partiallysurrounding the heater and the crucible, the cooling enclosure having aninternal surface, wherein the internal surface of the cooling enclosureis spaced from the heater by plural support elements each providingplural openings circumferentially spaced from one another along each ofthe support elements that the openings and space between the heater andthe internal surface of the cooling enclosure define an annularconductance channel.
 2. The vacuum deposition source of claim 1, whereinthe crucible comprises pyrolytic boron nitride.
 3. The vacuum depositionsource of claim 1, wherein the crucible comprises a second conicalportion.
 4. The vacuum deposition source of claim 1, comprising acrucible support assembly comprising a support flange removably mountedto the base flange and a crucible support cup supported relative to thesupport flange, wherein an end of the crucible opposite the effusionorifice is supported by the support cup.
 5. The vacuum deposition sourceof claim 4, wherein the crucible support assembly comprises anadjustment device configured to adjust the distance between the supportflange and the support cup.
 6. The vacuum deposition source of claim 1,comprising a heater support assembly having a support base operativelysupported relative to the base flange and engaged with an end of theheater.
 7. The vacuum deposition source of claim 6, wherein the heatersupport assembly comprises an adjustment device configured to adjust thedistance between the base flange and the support base.
 8. The vacuumdeposition source of claim 1, comprising a liquid cooling enclosureoperatively attached to the base flange at a first end of the liquidcooling enclosure and at least partially surrounding the crucible. 9.The vacuum deposition source of claim 8, comprising a conical coverpositioned at a second end of the liquid cooling enclosure opposite thefirst end of the liquid cooling enclosure, the conical cover comprisingan opening at an end of the conical cover positioned relative to an endof the crucible and an end of the conical portion of the heater.
 10. Thevacuum deposition source of claim 9, wherein the conical cover comprisespyrolytic boron nitride.
 11. The vacuum deposition source of claim 9,comprising plural layers of conical heat shielding material positionedadjacent to the conical cover.
 12. The vacuum deposition source of claim9, wherein the end of the conical portion of the heater extends past theend of the conical cover.
 13. The vacuum deposition source of claim 9,wherein the end of the crucible extends past the end of the conicalportion of the heater.
 14. A vacuum deposition source comprising: a baseflange configured to mount the vacuum deposition source to a vacuumchamber; a crucible operatively supported relative to the base flangeand configured to hold vacuum deposition material, the cruciblecomprising a cylindrical body portion, a conical portion, and aneffusion orifice; a heater operatively supported relative to the baseflange and at least partially surrounding the crucible, the heatercomprising a cylindrical body portion configured and positioned toprovide thermal radiation to at least a portion of the cylindrical bodyportion of the crucible and a conical portion configured and positionedto provide thermal radiation to at least a portion of the conicalportion of the crucible, the heater comprising a layered structurecomprising a pyrolytic graphite electrically resistive layer positionedbetween pyrolytic boron nitride electrically insulative layers; a liquidcooling enclosure operatively attached to the base flange at a first endof the liquid cooling enclosure and extending along at least partiallysurrounding the crucible, the cooling enclosure having an internalsurface; and a conical cover positioned at a second end of the liquidcooling enclosure opposite the first end of the cooling enclosure, theconical cover comprising an opening positioned relative to the effusionorifice of the crucible; wherein the internal surface of the liquidcooling enclosure is spaced from the heater by plural support elementseach providing plural openings circumferentially spaced from one anotheralong each of the support elements so that the openings and spacebetween the heater and the internal surface of the cooling enclosuredefine an annular conductance channel.
 15. The vacuum deposition sourceof claim 14, wherein the heater comprises a first heating zoneassociated with the cylindrical body portion of the heater and a secondheating zone associated with the conical portion of the heater.
 16. Thevacuum deposition source of claim 14, comprising a crucible supportassembly comprising a support flange removably mounted to the baseflange and a crucible support cup supported relative to the supportflange, wherein an end of the crucible opposite the effusion orifice issupported by the support cup and wherein the crucible support assemblycomprises an adjustment device configured to adjust the distance betweenthe support flange and the support cup.
 17. The vacuum deposition sourceof claim 14, comprising a heater support assembly having a support baseoperatively supported relative to the base flange and engaged with anend of the heater and an adjustment device configured to adjust thedistance between the base flange and the support base.
 18. The vacuumdeposition source of claim 14, comprising a cylindrical heat shieldassembly at least partially surrounding the heater.
 19. A vacuumdeposition source comprising: a base flange configured to mount thevacuum deposition source to a vacuum chamber; a crucible supportassembly comprising a support flange removably mounted to the baseflange and a crucible support cup supported relative to the supportflange; a crucible operatively supported by the support cup of thecrucible support assembly and configured to hold vacuum depositionmaterial, the crucible comprising a cylindrical body portion, a conicalportion, and an effusion orifice; and a heater operatively supportedrelative to the base flange independent of the mounting of the cruciblesupport flange to the base flange and at least partially surrounding thecrucible, the heater comprising a cylindrical body portion configuredand positioned to provide thermal radiation to at least a portion of thecylindrical body portion of the crucible, the heater being operativelysupported relative to the base flange by a heater support assemblyhaving a support base operatively supported relative to the base flangeand engaged with an end of the heater, wherein the heater supportassembly comprises an adjustment device configured to adjust thedistance between the base flange and the support base of the heatersupport assembly and for moving the heater relative to the crucible; acooling enclosure operatively attached to the base flange at a first endof the liquid cooling enclosure extending along and at least partiallysurrounding the crucible, the liquid cooling enclosure having aninternal surface; wherein the internal surface of the cooling enclosureis spaced from the heater by plural support elements each providingplural openings circumferentially spaced from one another along each ofthe support elements so that the openings and space between the heaterand the internal surface of the cooling enclosure define an annularconductance channel.
 20. The vacuum deposition source of claim 19,wherein the crucible support assembly comprises an adjustment deviceconfigured to adjust the distance between the support flange and thesupport cup, independently of adjustment of the heater relative to thebase flange.
 21. The vacuum deposition source of claim 19, comprising aconical cover positioned at a second end of the liquid cooling enclosureopposite the first end of the liquid cooling enclosure, the conicalcover comprising an opening at an end of the conical cover positionedrelative to an end of the crucible and an end of the conical portion ofthe heater.